The role of the building engineer within the development of energy systems – Dr David Jenkins

National Centre for Energy Systems Integration (CESI) Co-Investigator, Dr. David Jenkins, is a research specialist in sustainable buildings. In this week’s blog, he discusses how buildings can be considered in future energy systems and how his CESI research is shaping this consideration.

About the Author

Dr David Jenkins is an Associate Professor in the Institute of Sustainable Building Design at Heriot-Watt University. He has over 70 publications in the area of low- energy buildings, energy policy, and climate change adaptation. He has worked on a number of EPSRC projects concerned with the energy use of the built environment, such as Tarbase, Low Carbon Futures, ARIES and CESI and has contributed to a number of reports in these areas for UK and Scottish Governments. He is currently PI of the CEDRI project, looking to apply community energy analyses to case studies in India.

The built environment has always been of great importance in any discussion of carbon saving targets in the UK. 13% of UK carbon emissions emanate from heating/cooking in residential buildings alone[1]. 29% of emissions are linked to “energy supply” (including electricity supply to the built environment), with other sectors (e.g. “business” at 17% and “industrial processes” at 3%) also having energy consumption that is heavily linked to the built environment. Therefore, as we map out our future energy systems (gas/electricity grids and other energy pathways) we must have an understanding of the evolving energy demand characteristics of the diverse range of buildings that we occupy.

A practitioner with a particularly good understanding of this detail, the building engineer, often has their professional boundaries drawn around the building itself. Therefore, the sizing of a boiler, assessment of general building performance, and choices related to low-carbon design are not always placed in the context of other important factors within the energy supply chain.

Whilst this focus is to some extent defendable – the challenges of low-carbon building design are, in themselves, considerable – it does run the risk that crucial knowledge of building performance is not reflected in energy system modelling. This is particularly true when we investigate the steep vectors of change facing our energy systems in the coming decades. Coincident changes in climate, technologies, fuels, and operation, provide a landscape of uncertainty that must be consistently reflected in projections of every aspect of our energy system: supply, infrastructure/distribution, storage, and demand. For example, a future projection assuming the continued existence of an established mains gas grid for heating homes is not necessarily consistent with the installation of several million heat pumps for residential heating. The latter change should, therefore, be accompanied by an assumption on the supply-side that the gas grid will either be reduced in scale or used for something else. Policy in these different areas must also be similarly synergistic.

The building modeller is crucial to our understanding of energy demand but, with energy systems (e.g. National Grid) involving multiple actors from different disciplines, a key challenge is to provide guidance and future projections that are translated into different discipline-specific vernaculars. Integration across the disciplines must be reflected in modelling approaches, policy-making frameworks, and outputs. The CESI project, where novel modelling techniques are being used to explore the effect of future buildings on national energy systems, sees this as a key challenge in producing actionable guidance to a range of practitioners.

Another issue that often dissuades the traditional building modeller/engineer from interacting with wider energy system analysis is “scale”. Modelling a building is quite different to modelling buildings. Capturing the energy demand characteristics of a community of buildings (e.g. such as might be served by a substation) requires an understanding of the diversity of energy use. A “spikey” electrical demand profile of a single dwelling (showing kettle’s boiling and toasters toasting) is quite different to that of a 200-dwelling profile, where different behaviours and activities are summated together in a smoother profile. Likewise, asking a building engineer to consider the aggregated demand profile of, say, 200 gas boilers working at slightly different schedules is a step change from a detailed hourly profile of a single boiler. Yet this level of detail is particularly valuable when we consider what might happen to energy demand at specific times in the future. Will electric heat pumps create national electrical demand profiles that are more difficult to meet for energy suppliers? Or are such changes perfectly manageable providing storage and management solutions are utilised at the correct point in the network? And what happens if millions of people wish to home-charge their electric vehicles at similar times in the evening? What does a new residential electrical demand profile now look like for the UK? This, therefore, does not just require an understanding of scale, but also that of temporal resolution; daily averages of energy use will not indicate where and when such problems might be manifest, and what their solutions might be.

The future building engineer will be required to build on existing core skills to reflect the above context. Changes to energy supply (such as carbon intensity) will, ultimately, alter our assumptions of “good” and “bad” technologies for the built environment. Conversely, technological and behavioural change in the built environment will change our assumptions on how to supply that energy efficiently. This co-evolution of change across sectors is central to CESI and encapsulates the challenge to, but also the value of, multi-disciplinary energy system modeling.